Protectors for electric circuits



2 Sheets-SheetI l INVENTOR.

H 7 TO/EIVEX 4f. ors/us J. F/s TER BY A. J. FISTEIR PROTECTORS FOR ELECTRIC CIRCUITS Oct. 25, 1966 Filed sept. "z, 1962 Oct. 25, 1966 A. J. FxsTER PROTECTORS FOR ELECTRIC CIRCUITS Filed Sept. 7. 1962 2 Sheets-Sheet 2 I n4 96 l`, 92

0 7T g. 2 E'. Z

NVENTOR.

United States Patent O Ware Filed sept. 7, 1962, ser. No. 222,010 s Claims. (ci. 20o-120) This invention relates to improvements in Protectors for Electric Circuits. More particularly,y this invention relates to improvements in electric fuses.

It is, therefore, lan object of the present invention to provide an improved electric fuse.

It is frequently desirable to provide electric fuses that have la plurality of fusible elements of relatively small cross section; tand, in Irecognition of that fact, electric fuses have been proposed which had a plurality of fusible elements of relatively srnall cross section connected to and extending between the terminals thereof. In some of those electric fuses, the fusible elements were secured to the terminalsand then the cylindrical casings of those electric fuses were telescoped over those termina-ls and over those fusible elements. To enable the casings of those electric fuses to be telescoped over the terminals land over the fusible elements of those electric fuses without distortion or deflection of those fusible elements, those fusible elements had to have substantial cross sections and there had to be a substantial number of those fusible elements. It would be desirable -to provide Ian electric fuse which could have fusible elements with very srnall cross sections and which could have as few fusible elements as desired, 'and yet could prevent deflection or distortion of those fusible elements. The present invention provides such an electric fuse; and it is, therefore, an object of the present invention to provide an electric fuse which can' have fusible elements with very small cross sect-ions and which can have as few fusible elements as desired, and yet can prevent deection or distortion of those fusible elements.

The present invention provides |an electric fuse with electric `fuse units that have pluralities of fusible elements secured to the terminals thereof; and those electric fuse units constitute self-contained sub-assemblies for that electric fuse. The terminals of those electric fuse units have the axes thereof ygenerally Iparallel to the path of movement which they must follow Vas those electric fuse units are assembled with the housing of that electric fuse. This means that the forces which tend to resist the assembling of those electric fuse units with that housing will be applied directly to, and will be readily withstood by, those terminals. Consequently, substantially none of the forces which resist the assembling of the electric fuse units with the housing for that electric fuse need be withstood by the fusible elements of that electric fuse. It is, therefore, an object of the present invention to provide an electric fuse With electric fuse -units which have terminals that have the [axes thereof generally parallel to the path of movement Which those terminals must follow as they 'are assembled with the housing of that electric fuse.

Some electric fuses can be subjected to extremely heavy shocks. For example, electric fuses that are mounted in military vehicles such as war ships, tanks, and the like can be subjected to extremely heavy shocks. Also, any electric fuse can be subjected to a heavy shock if it is accidentally dropped onto la hard surface. Moreover, any electric fuse can be subjected to repeated shocks by exposing it to heavy vibrations. It would be desirable to provide an electric fuse which could withstand extremely heavy shocks and which could also withstand repeated shocks. The present invention provides such fuse which has a fan electric yfuse by resiliently mounting the terminals of thatv electric fuse within the housing of that electric fuse. It is, therefore, an object of the present invention to provide an electric fuse wherein the terminals are resiliently mounted within the housing for that electric fuse.

The terminals of the electric fuse provided by the present invention are resiliently supported by yieldable elements which also serve as seals for openings in the housing of that electric fuse. Those yieldable elements thus perform ,a dual function. It is, therefore, an object of the present invention to provide Ian electric fuse with yieldable elements that seal openings in the housing of that electric fuse and also resiliently support the terminals of that electric fuse.

The present invention provides a polyphase electric fuse which has la plurality of individual and separate electric fuse units mounted within one housing. Such a polyphase electric fuse can have a heavy Iand strong housing for the plurality of electric fuse units and yet have relatively small overall dimensions. Further, such a polyphase electric fuse can provide simultaneous connection of `the plurality of electric fuse units with the circuits which they are to protect, land can a'lso provide simultaneous separation of that plurality of electric fuse units from those circuits. It is, therefore, an object of the present invention to provide a polyphase electric plurailty of individual and separate electric fuse ru-nits mounted within one housing.

The housing for the polyphase electric fuse provided by the presen-t invention has partitions which isolate the various fuse units from each other. Those partitions perform the dual :functions of preventing ashover between adjacent electric fuse units and of holding arcqnenching lfiller 'adjacent the fusible elements of each electric fuse unit. Moreover those partitions will keep pressures, which will be created during the blowing of the lfusible elements of any one of the electric fuse units, from being dissipated into the areas surrounding the other electric fuse units; and hence will facilitate prompt quenching of 'any 'arcs that tend to form as t-he fusible elements of that electric fuse unit blow. It is, therefore, Ian object of the present invention to provide a polyphase elec-tric fuse with a housing that has partitions which isolate a plurality of electric fuse units from each other.

The housing of the elec-tric fuse provided by the present invention has the top thereof formed so it can be completely open. This is important because it facilitates complete and full filling of that housing with arc-quenching lille-r, as by preventing the creation of filler-free voids which could exist if that housing had to be iilled through a small opening. It is, therefore, an object of Ithe present invention to provide a housing for an electric fuse which can have the top thereof completely open to facilitate the illing of that housing with arc-quenching liller.

The present invention closes the open top of the housing for the electric fuse with a rigid closure which is underlain by ya yieldable plate. That yieldable plate is one of the yieldable elements which resiliently support the terminals of that electric fuse and which seal the openings of the ho-u-sing for that electric fuse. That yieldable plate also provides a compressive force for the arc-quenching ller disposed Within .the housing for that electric fuse; and that compressive force increases the intimacy of contact between that arc-quenching filler and the surfaces of the fusible elements. Such increased intimacy of contact is important because it increases the ability of that are-quenching filler to :absorb heat from those fusible elements, and thereby makes it possible to use fusible elements of very small cross section. It is, therefore, an object of the present invention to close the open top of a housing for an electric-fuse with a rigid closure which is underlain by a plate of yieldable material.

The terminals for each electric fuse unit provided by the present invention serve as plug-in terminals for that electric fuse unit. The projecting ends of those terminals are spaced apart a distance which will prevent arcs'from forming between those projecting ends, and which will also keep -current from leaking between those projecting ends. Those terminal-s are bent intermediate the ends thereof to space the remaining portions of those terminals further apart; and the resulting increased spacing between the remaining portions of those terminals facilitates the quenching of any arcs that might form as the fusible elements blow to open the circuit. It is, therefore, an object of the present invention to provide a-n electric fuse unit wherein the terminals have projecting ends th-at serve as plug-in terminals and wherein those terminals are bent intermediate the ends thereof to provide a greater spacing between the remaining portions thereof than is provided between the projecting ends thereof,

The fusible elements ofthe electric fuse provided by the present invention are arranged to provide a zigzag pattern; and such a pattern is important because it provides maximum spacing between the various fusible elements. That spacing makes it possible for each fusible element to have a large amount of arc-quenching filler disposed in intimate engagement with it, and thereby makes certain that each fusible element can blow without undue arcing. It is, therefore, an object of the present invention to arrange the fusible elements of an electric fuse to provide `a zigzag pattern.

The indicator for each electric fuse unit provided by the present invention is held by a strain wire that extends perpendicularly of the fusible elements `of that electric fuse unit. That strain wire is intended to fuse and release the indicator whenever those fusible elements blow to open the circuit; and that strain wire is connected so it is in parallel with those fusible elements. That strain wire will be subjected to a greatly increased voltage when the fusible elements blow to open the circuit; and, in addition, that strain wire will, because it extends perpendicularly of those fusible elements, be exposed to heat as those fusible elements blow to open the circuit. The overall result is that prompt and certain fusing of the strain wire is effected. It is, therefore, an object of the present invention to provide a strain wire which extends perpendicularly of the fusible elements of an electric fuse unit.

Thev electric fuse units provided by the present invention have plates of insulation which extend between, and are supported by, the terminals ofthose Velectric fuse units. The forces which are applied to the strain wires of those electric fuse units are withstood by those plates of insulation; and hence the fusible elements of those electric fuse units are not subjected to the forces which are applied to the strain wires of those electric fuse units. It is, therefore, an object of Athe present invention to provide plates of insulation which extend between, and are supported by, the terminals of electric fuse units and which withstand the forces which are applied t the strain wires of those electric fuse units.V

Other and further Vobjects and advantages of the present invention should become apparent from an examination of the drawing and accompanyingdescription.

In the drawing and accompanying description a preferred embodiment of the present invention is shown and described but it is ,to be understood that the drawing and accompanying description are for the purpose of illustration -only and do not limit the invention and that the inventionwill be defined by the appended claims.

In theV drawing, FIG. l is a side elevational View of one form of electric fuse that is made in accordance with the principles and teachings of the present invention,

FIG. 2 is a partially broken-aw-ay, partially sectioned,

4 View of the right-hand end of the electric fuse of FIG. 1

J FIG. 3 is a View of the bottom of the electric fusel of FIG. 1,

FIG. 4 is a plan view of the electric fuse of FIG. l, FIG. 5 is another partially broken-away, .partially sectioned, view of the right-hand end of the electric fuse of FIG. 1,

FIG. 6 is a partially broken-away, partially sectioned, plan View of the electric fuse of FIG. 1,

FIG. 7 is a partially broken-away, partially sectioned, view of the electric fuse of FIG. 1, and it is taken along the broken plane indicated by the broken line 7-7 in FIG. `6,

FIG. 8 is a sectional view through the electric fuse of FIG. l, and it is t-aken along the plane indicated by the line 8-8 in FIG. 7,

FIG. 9 is an end elevational View of one of the electric fuse units disposed within the electric-fuse of FIG.1,

FIG. 10 is a sectional view through the electric fuse unit of FIG. 9, and it is taken along theplane indicated bythe line 10-10 in FIG. 9,

FIG. 11 is a sectional View, on a larger scale, through the indicator of the electric fuse unit of FIG. 9, and

FIG. 12 is a sectional view through the upper part of the electric fuse of FIG. 1.

Referring to the drawing in detail, the numeral 26 generally denotes a housing for one form of electric fuse A that is made in accordance with the principles and teachings of the present invention. That housing is made of insulating material and it has two passages 22 extending through it; and those passages are disposed adjacent two diagonally-opposed corners of that housing. Each of those passages has a larger diameter lower end 24 and has a shoulder 26 at the upper end of that larger diameter lower end. The housing 20 also has two passages 28 extending through it, and those openings are disposed adjacent the other two diagonally-opposed corners of that housing. Each of the passages 28 has a larger diameter upper end 36, a larger diameter lower end 32, a shoulder 34 at the lower end of the larger diameter upper end 30, `and a shoulder 36 at the upper end of the .larger diameter lower end 32.

The ends walls of each Vof those recesses inclined slightly relative to each other so the lower ends thereof are slightly closer together than are the upper ends thereof. The side walls of each of those recesses incline slightly relative to each other so the lower ends thereof are slightly closer together than are the upper ends thereof. Abutments 40 are provided at the corners of the recess 38, and those abutments extend down to the bottom of that recess. Similarly, the recess 42 has abutments 44 at the corners thereof, and those abutments extend down to the bottom of that recess. The recess 46 has abutments 48 at the corners thereof, and those abutments extend down to the bottom of that recess. The faces on each of the abutments 40, 44 and 48 subtend angles of substantially ninety degrees. The abutments 40 will all incline slightly relative to each other so the upper ends thereof are spaced further apart than are the lower ends thereof.

A.partition 50 isolates the recess 38 from the recess 42, and a parti-tion52 isolates the recess 42 from the recess 46. A generally cylindrical boss 54 is provided in the housing 20, and part of that boss extends into the recess 38 while another part of that bossextends into the recess 42. That boss is located adjacent the bottoms of the recess 38 and 42; and a cylindrical socket 56 is provided in the bottom of that boss. That socket opens to the bottom face of the housing 20; and it is shown in solid lines in FIG. 3 and in dotted lines in FIG. 8.

Slots 58, 60, 62, 64, 66 and 68 are formed in the bottom l a slot 106 is provided in that of the housing 20; and the slots 58 and l64 communicate with the recess 38, the slots 60 and 66 communicate with the recess 42, and the slots 62 and 68 communicate with the recess 46. All of th-ose slots are elongated and narrow; and the slots 58, 60 and 62 are alined and the slots 64, 66 and 68 are alined. Further, the slot 58 is in register with the slot 64, the slot 60 is in register with the slot 66, and the slot 62 is in register with the slot 68.

The numeral 70 generally denotes a metal terminal of one of the electric fuse units of the electric fuse of FIG. l. That terminal has a notch 72 in the top thereof, as shown particularly by FIGS. 6 and 7. An offset 74 is provided intermediate the top and bottom of the terminal 70; and that offset spaces the lower portion of that termi-nal to the right of the upper portion of that terminal, as that terminal is viewed in FIG. 9. The l-ower portion of the terminal 70 has shoulders 78 defining a reduced-width prong 76. The bottom edge of that prong is tapered, as shown particularly by FIG. 9. Recesses 79 are formed in the righthand face of the terminal 70, as that terminal is viewed in FIG. 9; and those recesses are grouped in four verticallyalined rows.

The numeral 80 denotes a second metal terminal for the said one electric fuse unit; and that terminal is a mirror-image of the terminal 70. The terminal 80 has a notch 82 in the top thereof, as shown particularly by FIGS. 6 and 9; and it has an offset 84 intermediate the top and bottom thereof. That offset spaces the lower portion of that terminal to left of the upper portion of that terminal, as that terminal is viewed in FIG. 9. The lower portion of the terminal 80 has shoulders 88 which define a reduced-width prong 86; and the bottom edge of that prong is tapered, as shown particularlyv by FIG. 9. Recesses 90 are formed in the left-hand face of the terminal 80, as that terminal is viewed in FIG. 9; and those recesses are grouped in four vertically-alined rows as shown by FIG. l0. The recesses 79 in the terminal 70 are in register with the recesses 90 in the terminal 80.

The numeral 92 denotes a plate of insulation which has ears 94 that are dimensioned to extend into the notches '72 and 82, respectively, of the terminals 70 and 80. The end faces of those portions of the plate 92 whichextend laterally outwardly beyond the ears 94 will abut the confronting faces of the terminals 70 and 80, and will thus space the upper ends of those terminals apart a fixed and predetermined distance. The plate 92 has an opening 96 therein, as .shown particularly by FIG. and that opening is about midway between the ends of that plate.

The numeral 100 denotes a second plate of insulation; and` that plate is slightly shorter than the plate 92. Slots 102 and 104 are formed in the plate 100; and the slot 102 accommodates the prong 76 at the lower end of the terminal 70, while the slot 104 accommodates the prong 86 at the lower end of the terminal 80. The engagements between the sl-ots -102 and 104 of plate 100 and the prongs 76 and 86, respectively, of terminals 70 and 80 will be Snug; and hence the plate 100 can coact with the plate 92 to provide a fixed spacing between the terminals 70 and 80. An opening 108 is provided in the plate 100, approximately midway between the ends of that plate; and

plate intermediate the opening 108 and one end of that plate, as shown particularly by FIG. 9.

The numeral 110 denotes metal fusible elements of small -cross section that have the opposite ends thereof soldered within the recesses 79 and 90, respectively, of the terminals 70 and 80. As indicated particularly by FIG. l0, the recesses 79 and 90 in the two outer verticallydirected rows of, recesses are staggered with respect to the recesses 79 and 90 in the two inner vertically-directed rows of recesses; and this means that the fusible elements 110 in the two outer vertically-alined rows of fusible elements will be staggered with respect to the two inner vertically-alined rows of fusible elements. This is desirable because it increases the total amount 0f filler which can surround each fusible element.

The numeral 112 denotes a metal connector which has a slot in one end thereof to accommodate the prong 86 of the terminal 80, and which has a hole therein that can be set in register with the opening 108 in the plate 100. The connector 112 has a portion thereof disposed within the slot 106 in the plate 100, and is thus tixedly held in assembled relation with that plate.

The numeral 114 denotes a cup-shaped housing of metal, and it has a tubular extension 116 extending downwardly from the closed end thereof7 as shown particularly by FIGS. 10 and 1l. That tubular extension is dimensioned to telescope downwardly into the opening 96 in the plate 92; and that tubular extension will project below the lower face of the plate 92.

A shunting strip 134 has la loop at one end thereof, and that loop telescopes over the tubular extension 116 on the housing 114. That loop will be telesc-oped over that tubular extension and will be soldered to that tbular extension, after that tubular extension has been telescoped downwardly into the opening 96 in the plate 92. The free end of the shunting strip 134 extends along the bottom face of the plate 92 and then passes into the notch 72 at the top of the terminal 70. Solder will preferably be-used to connect that free end of that shunting strip to the terminal 70. The shunting strip 134 will maintain the cup-shaped housing 114 in assembled relation with the plate 92.

The numeral 118 denotes a circular disk of -a resilient material such as neoprene; .and that disk is dimensioned to fit snugly within the interior of the housing 114. A disk 120 of metal is dimensioned to lit loosely within the interior of the housing 114; and the disk 120 overlies the disk 118. A helical compression spring 1,22 is dimensioned to fit loosely within the interior of the housing 114; and lower end of that spring hears against the upper face of the disk 120. The upper end of ythat spring abuts a radially directed, circumferentially extending flange 126 on an indicator 124. ".[lhat indicator is -generally cylindrical in form and it has an axially-directed recess at the geometric center thereof. In addition, that indicator has a passage which extend ldownwardly from the bottom of that recess to the lower face of that indicator. A pin 128, which has a hea-d at the upper end thereof and whichhas an opening through the lower end thereof, is telescoped `down into the indicator 124 so the head thereof is lodged within the recess in that indicator and so -t-he shank thereof extends downwardly through the passage in that indicator.

A wire 130 has the lower end thereof wound around the bottom turn of `the helical compression spring 122; and that wire is wound around that turn lso intimately that current can flow from that wire into that spring. The

v upper end of the Wire 130 passes through the opening in the lower end of the pin 128. A strain wire 132 also has the upper end thereof extending through the opening in the lower end of the pin 128; and solder will preferably be used to secure the upper ends of the wires 130 and 132 in position within that opening. The lower end of the strain wire 132 extends downwardly through an opening in the disk 120, through an opening in the disk 118, through the tubular extension 116 of the housing 114, through the opening 108 in the plate 100, and through the opening in the conductor 112. The diameters of the openings in the disks 118 and 120 are small enough to .prevent the passage of foreign material lthrough those openings after the strain wire 132 has been passed through those openings, but those diameters are large enough to permit the strain wire 132 to move freely relative to those disks.

Generally square seals of resilient material are provided with slots therein. The slot in one of those seals accommodates the prong 76 of the terminal 70, and the slot in the other of those seals accommodates the prong fusible elements 110.

7 86 of the terminal 80. Those seals abut the lower face of the plate 100, as shown by FIG. 9.

After they have been assembled, the terminals 70 and 80, the plates 92 and 100, the fusible elements 110, the cup-shaped housing 114, the spring 122, the disks 118 and 120, the indicator 124, the pin 128, the wire 130, the strain wire 132, the connector 112, and the shunting strip 134 will constitute yan electric fuse unit which can be handled as an entity. In assembling that electric fuse unit, the connector 112 will have the free end thereof telescoped down through the opening 106 in the plate 100. Thereafter, that connector will have the opening in thatfree end alined with the opening 108 in the plate 100 while the slot in that'connector will be alined with the slot 104 in that plate. Theftubular extension 116 on the cup-shaped housing 114 will be telescope-d downwardly into the opening 96 in the plate 92; and then the loop at one end of the shunting strip 134 will be telescoped over that tubular extension. Solder will then be applied to that loop and to that tubular extension to secure the housing 114 and the shunting strip 134 to ea-ch other and to the plate 92. The pin 128 will be telescoped downwardly through the recess in the indicator 124 until the head of that pin -abuts the shoulder between that recess and the passage through that indicator. The upper ends of the wires 130 and 132 will then be passed thro-ugh lthe opening in the lower end of that pin; Iand solder will be used to xedly secure the upper ends of these wires to that pin. The lower ends of the wires 130` and 132 will then be telescoped downwardly through the helical spring 122, and the top turn of that spring will be pressed against the radially-directed, circumferentially-extending flange 126 on the indicator 124. Y

The lower end of the wire 130 will then be wrapped intimately around the bottom turn of that spring. At this time, the lower end of the strain 132 Will be telescoped through the opening in the disk 120 `and then through the opening in the resilient disc 118.

The prong 76 of the terminal 70 will then be telescoped ldownwardly through the opening 102 in the vplate 100 until the shoulders 78 of that terminal abut the upper Iface of that plate. The prong 86 of the terminal 80 will be telescoped downwardly through the slot in the connector 112 and through the opening 104 in the plate 100 until the shoulders 88 of that terminal abut the upper face of that connector. At this time, the plate `100 will provide the desired spacing between the lower ends of the terminals 70 and 80. The plate 92 will then be disposed between the upper ends of those terminals, and the ears 94 of that plate will be lodged within the notches 72 and 82 in those terminals. When the upper ends of the terminals 70 and 80 are pressed against the ends of the plate 92, that plate an-d the plate 100 will serve to hold those terminals in precise registry with each' other and will serve to hold the confronting faces of those terminals spaced apart the desired distance. At this time, the -fusible elements 110 can have the opposite ends thereof set within the recesses 79 and 90 in those confronting facesthose fusible elements being bowed slightly to enable them to move into position where their opposite ends can be set within those recesses. Once the opposite ends of those fusible elements have been set within the recesses 79 and 90, the forces which were used to bow those fusible ele ments can be released; and thereupon those fusible elements will straighten out. Solder will be suitably lapplied tothe ends of the fusible elements 110 and to the confronting faces of the terminals 70 and 80 to bond those fusible elements to those terminals.

At this time, the free end of the strain wire 132 will be passed downwardly through the cup-shaped housing 114,

Y through the tubular extension 116 on that housing, and

then between the two innermost vertically-alined rows of That free end of that strain w-ire will then be passed downwardly through the opening 108 in the plate 100 and through the corresponding opening in the connector 112. As that free end of that strain wire 8 is so moved, the disks 118 and 120, the helical compression spring 122, the wire 130, the pin 128, and the lower end of the indicator 124 will be moved down into the cupshaped housing 114. The free end of the strain wire .132 will be pulled downwardly far enough to compress t'he helical compression spring 122 and to move the upper end of the indicator 124 close to the upper end of the cup-shaped housing 114. Preferably, that f-ree end of that strain wire will be moved downwardly far enough to leave less than three-sixteenths of an inch of the upper end of the indicator 124 projecting above the upper end of the cup-shaped housing 114. At this time, the free end of the strain wire 132 will be bent into eng-agement with 4the lower face of the connector 112, and will have a portion thereof soldered to that lower face. Once the solder has hardened, the excess length of the str-ain wire 132 can be cut away.

The resulting electric fuse unit can be readily handled as an entity. The seals 115 will then be telescoped upwardly over the prongs 76 and 86, respectively, of the terminals 70 and 80. The same assembling procedure can be followed in assembling the other two electric fuse units for the electric fuse of FIG. l.

The rst of the three electric fuse units will be telescopeddownwardly into the recess 38 in the housing 20; and the abutments 40 at the four corners of that recess will receive the edges of the terminals 70 and 80 and thereby guidethe telescoping movement of that-electric fuse unit into that recess. The inclination of the abutments 40 of that recess relative to each other facilitates the telescoping of that electric fuse unit into that recess. The plate 100 :is dimensioned so the prongs 76 and 86 of the terminals 70 and 80, respectively, will be in register with the slots 58 and 64 in the bottom of the housing 20. As the result, those prongs will extend through the slots 58 and 64 as that electric fuse unit is moved toward the kbottom of the recess 38.

As shown particularly by FIG. 7, the seals 115 directly abut the bottom yof the recess 38 and the shoulders 78 and 88, respectively of the terminals 70 and 80. In addition, those seals closely engage the faces of the prongs 76 and 86 of those terminals. Consequently, those two resilient seals coact with the prongs 76 Iand 86 of the terminals 70 and 80 to effectively close and seal the slots 58 and 64 in the bottom of the housing 20. Also as indicated by FIG. 7, the top edges of the terminals 70 and 80 are flush with the top face of the housing 20 when the electric fuse unit is fully telescoped down into the recess 38 and a moderate compressive force is applied to the seals 115.

The other two electric fuse units will be telescoped down into the recesses 42 and 46. The prongs of 'one of those electric fuse units Will project through the slots 60 and 66,

. and the prongs of the other .of those electric fuse units will project through the slots 62 and 68 inthe bottom of the housing 20. The prongs of the three electric fuse units will be alined as indicated by FIGS. l-3. Also, the cup-shaped housings and indicators of those electric fuse units will be alined, as -indicated particularly by FIGS. 4, 6 and 7. As indicated by FIG. 7, the upper ends of those indicators will normally be at the same level.

A closure 136 has three sockets 138 which accommodate the upper ends of the cup-shaped housings 114 ofthe various electric fuse units. Cylindrical openings eX- tend upwardly from the sockets 138; and those openings accommodate the upper ends of the indicators 124 of those electric fuse units. The diameters of 4the openings 140 are made sufficiently large, relative to the upper ends of the indicators 124, to permit those indicators to move freely in those openings. The sockets 138 and the openings 140 are formed so they define shoulders which can overlie the tops of the cup-shaped housings 114 and can hold the plates 92 in assembled relation with the terminals 70 and 80. The openings 140 are formed so they will register precisely with the indicators 124 of the three electric fuse units; and hence there will be no binding forces 9 which could interfere with the upward movement of any of the indicators 124.

The closure 136 has openings 142 adjacent two diagonally-opposed corners thereof, and those openings have shoulders 144 intermediate the ends thereof, as shown particularly by FIG. 5. When the closure y136 is .assembled with the housing 20, the openings 142 will be in register with the passages 22 in the housing 20. The closure 136 also has openings 146 adjacent the other diagonally-opposed corners thereof, and those openings have shoulders 148 intermediate the ends thereof. When the closure 136 is assembled with the housing 20, the openings 146 will bein register with the passages 28 in the housing 20.

Finger receiving recesses 150 are provided in the elongated sides of the closure 4136; and those recesses are elongated and are triangular in cross section. Those recesses are intended to receive the tips of the fingers of persons installing the polyphase fuse of the present invention within the receptacle for that fuse. That receptacle will have fuse clips which can accommodate the prongs 76 and 86 at the lower ends of the terminals 70` and 80 of the various electric fuse units. Those fuse clips will be disposed adjacent the bottom of the recess in that receptacle, and that recess will be large enough to accommodate the greatest part of the housing 20. However, that recess will be shallow enough to enable the closure 136 to project upwardly beyond the upper surface lof that receptacle.

The numeral 152 denotes a resilient pad which is generally rectangular in plan' but which has the elongated sides thereof cut-away to the depth of the finger receiving recesses 150, as shown particularly by FIG. 2. Consequently, the upper and lower faces of the pad 152 will not be exposed, and only` the edges of that pad will be exposed. The pad 152 has three openings which are alined with, and which telescope over, the cup-shaped housings 114 of the three electric fuse units. Also, that pad has four openings adjacent the corners thereof; and two of those openings will be in register with the passages 22 in the housing and the two of these openings will be in register with with the passages 28 in that housing. While the passages 22 are smaller than the larger diameter upper ends 30 of the passages 28, all of the openings -in the pad 152 are made large enough to match the diameters of the upper ends 30 of the passages 28. l

Once the three electric fuse units have been disposed within the recesses 38, 42 and 46 of the housing 20, a suitable filling material 162, shown in FIGS. 8 and 12, will be introduced into each of those recesses. That filling material will pass downwardly between the elongated sides of the plates 92 of those electric fuse units and the adjacent side walls of the recesses 38, 42 and 46. That filling material will iiow freely into those recesses land will surround and imbed the fusible elements 110 and the strain wires 132. In addition, that filling material will completely cover the confronting faces of the terminals 70 and 80, will cover the upper face of the plates 100, will cover the lower and upper faces of the plates 92, 'and will also fill the spaces between the outer faces of the terminals 70 and 80 of the three electric fuse units and the end walls of the recesses 38, 42 and 46. The filling material 162 will coact with the electric fuse units to completely fill the recesses 38, 42 and 46; and the top of that filling material will be flush with the top surface of the housing 20.

At this time the resilient pad 152 will have the three central openings thereof telescoped downwardly over the indicators 124 and the cup-shaped housings 114 of the three electric fuse units. Two of the remaining four openings in that pad will -be in register with the passages 22 in the housing 20, Iand the other two of these remaining openings in that pad will be in register with the passages 28 in that housing. The closure 136 can then have the sockets 138 thereof telescoped downwardly over the upper ends of the cup-shaped housings 114 of the three electric fuse units. As those sockets are telescoped'downwardly over the upper ends of those cup-shaped housings, the openings in that closure will telescope downwardly over the upper ends of the indicators 124. The openings 142 in the closure 136 will be in register with the passages 22 in the housingv20, and the openings 146 in that closure will be in register with 4the passages 28 in that housing. The closure 136 will be held in assembled relation with the resilient pad 152 and with the housing 20 by elongated sleeves 158 which have flanges at the upper ends thereof that abut the shoulders 144 intermediate the upper and lower ends of the openings 142 in that closure. The lower ends of those sleeves will be spun or riveted over into intimate enga-gement with the shoulders 26 adjacent the upper ends of the larger diameter lower ends 24 of the passages 22 in the housing 20. As the lower ends of the sleeves 158 are being spun or riveted over into engagement with the shoulders 26, a heavy pressure will be applied to the closure 136 and to the housing 20 to compress the resilient pad 152. That pressure will be sufficient to make the edges of that pad considerably thinner than they lare in their un-stressed state; and that lpressure will cause that pad to apply compressive forces to the filling material 162 within the recesses 38, 42 and 46. This means that the filling material 162 will =be forced into very intimate engagement with the fusible elements 110. The engagement between the `sleeves 158 and the shoulders 26 and 144, respctively, of the housing 20 and of the closure 136 will be so intimate that the resilient pad 152 will continue to apply substantial compressive forces to the filling material 162 even after the forces which initially urged the closure 136 toward the housing 2t) are relieved. At this time, sleeves 154 which have flan-ges at the upper ends thereof and which lare internally threaded can be telescoped downwardly into the openings 146, as shown particularly by FIG. 5. Then machine screws 156 can be telescoped upwardly through the passages 28 until the threaded shanks thereof engage and are held by the threads at the interiors of the sleeves 154 and the heads thereof abut the shoulders 36 at the upper ends of the large diameter lower ends 32 of the passages 28. The screws 156 `are short enough so the shanks thereof engage only a few of the threads of the sleeves 154; and this is desirable because it leaves the rest of the threads of those sleeves unfilled.

The ipolyphase fuse of the' present invention will then be complete -and ready for installation and use. To installl that fuse, lche installer will insert his fingertips in the finger-receiving recesses of the closure 136 and will then direct the prongs 76 and `86 of the terminals 70 and 80 toward the clips within the receptacle for that fuse. The `sides of that receptacle will help aline the prongs 76 and 86 of the terminals 70 and 80 with the clips for those prongs; and hence the installer need only push on the closure 136 to seat those prongs within those clips. Thereafter the instal-ler will telescope elongated machine screws 160 through the sleeves 158 within the passages 22 in the housing 20. The threaded Shanks of those machine screws will project downwardly beyond the bottom face of the housing 20 and will engage threads within threaded sockets in that receptacle. Those screws'will be a-ble to hold that rfuse solidly in position within the receptacle for that fuse despite shocks of all kinds.

To remove the fuse from its receptacle, it is only necessary to withdraw the screws 160 from the sleeves 158 and to pull outwardly on the fuse. In many cases, the forces which the installer will apply to the fuse by inserting his fingertips in the finger-receiving recesses 150 will be sufiicient to withdraw the fuse from its receptacle. However, if unusually stiff fuse cli-ps are encountered, the installer can withdraw the screws 160 from their positions within the sleeves 158 and then thread the threaded Shanks thereof into the unfilled threads of the sleeves 154. At such time the upper ends of the screws 160 will project upwardly beyond the top surface of the closure 136, as shown particularly by FIG. 5; and those upper ends can be gripped by pliers to enable lsufficiently large withdrawing forces to be applied to the fuse to vwithdraw that fuse from its receptacle.

The polyphase fuse provided by the present invention can provide full protection for polyphase equipment and yet is small and compact. For example, a fuse that can 'protect polyphase equipment can be made with a housing that is three and three-quarters inches long, two and one-half inches wide, and two `and one-half inches deep. r[he small size of that fuse is important because space is frequently at a premium in electric-al installations.

By forcing the lling material 162 into unusually intimate enga-gement with the fusibile elements 11i), the present invention increases the Iheat transference between those fusibile elements and that filling material. That increased heat transference is Iimportant because it enables those fusible lelements to dissipate their heat quite rapidly, and thus makes it possible to use fusible elements of unusually small cross-section. Such fusible elements are v able to respond to ovenloads to provide extremely rapid opening of the circuit, and can thus provide highly desirable current-limiting characteristics.

Itwill be noted that the shoulders 78 and 88, respectively, of the terminals 70 and `Sti are immediately adjacent the bottoms of the recesses 38, 42 and 46 in the housing 2li-those shoulders being separated from those bottoms only by the seals 115. Further, it will be noted that the top ends of the terminals 70 and 80 Kare immediately ad- Y jacent the lower face ofthe closure 136-those upper ends being separated from that llower face only by the pad 152. Since the seals 115 and the pad 152 are under compressive forces, those `seals land that pad will be of reduced thickness and of Iincreased stiffness. Consequently, the bottoms of the recesses' 38, 42 and 46 and the @lower face of the closure 136 will coact with those seals and with that pad to substantially prevent vertical movement of the electric fuse units relative to the housing 20. In addition, it will be noted that the abutments '40 intimately engage the side edges of the terminals 70 and lSli; and hence those abutments substantially prevent any jmovement of the electric fuse units longitudinally of the housing 20. Furthermore, it should be noted that the portions of the terminals 70 and S0 `adjacent the offsets 74 and 84 of those terminals abut the lower portions of the end walls of the recesses 38, 42 and 46 of the housing 20. Moreover, it will be noted that the filling mate- .rial 162 also lills the spa-ces between the end walls of the recesses 38, 42 and 46 and the outer faces of the terminals 70 and 80. The overall result is that the terminals 70 and `8() of the electric fuse units are held against appreciable movement relative to the housing 20. This is important because it keeps any and Iall forces which are applied to the housing 20, during the telescoping of the prongs 76 and 86 of the terminals 70 and S0 into and out of the fuse clips therefor, from applying hurtful forces to the fusible elements 110 or to the strain wires 132 of the various electric fuse units.

The seals 115 and the pad 152 coact with the prongs 76 and 86 of the terminals 70 and 80 and with the closure 136 to positively seal the housing 20 against any loss of filling material 162. The resilient disks 118 keep the filling material 162 from entering the cup-shaped housing 114, and thus keeps the filling material 162 from interfering with the movement of the turns of the spring 122. Furthermore, the seals 115, the pad 152 and the disk 118 coact to substantially prevent the venting of any gases andvapors which may be generated when the fusible elements 110 open the circuit. At the time the fusible elements 110 of any or all of the electric fuse units blow, the lling materials 162 will act vto quench any arcs that may form.

time prior to their insertion into the recesses 3S, 42 and 46 of the housing 20. Further, the use of such electric fuse units makes it possible for the pad 152 to apply compressive forces to the filling material 162 and thereby provide a desirable intimacy of engagement between that filling material and the fusible elements 110.v

Whenever, the fusible elements 110 of one of the electric fuse units open to interrupt the circuit, substantial amounts of current will begin to flow through the. strain wire 132 of that electric fuse unit. Specifically, as the fusible elements 110 of any one of the'electric fuse units open, current will flow from the prong 76 of the terminal '70 via that terminal, the shunting strip 134, cup-shaped housing 114, helical compression spring 122, wire 136, strainwire 132, connector 112, and the prong S6 of the terminal 80. That flow of current will immediately cause the strain wire 132 to fuse; and thereupon the helical 4compression spring 122 will force the indicator 124 of that electric' fuse unit to move to the raised position indicatedv by dotted lines in FIG. 2. The movement of that indicator to that extended position will provide a readily visible indication to the maintainence man or installer that the electric fuse unit with which that indicator is associated has opened the circuit. Depending upon load conditions, one, two or three of the electric fuse units within the housing 20 can operate to open the circuit. When lthe maintenance man or installer sees one or more of the indicators 124 in extended position, he will remove the screws 160, will remove the polyphase fuse, will insert a replacement polyphase fuse, and will then reinsert the screws 160.

The partitions 50 and 52 between the recesses 32, 42 and 46 of the housing 2G perform the dual functions of serving as walls for the individual recesses and also as separators for the phases ofthe polyphase circuit. The tightly-packed filling material 162 helps support and stilfen the partitions 50 and 52. The overall result is that even when the fusible elements 110 of just one of the electric fuse units act to open the circuit, the partitions 50 and 52 will be amply 4strong enough to isolate the` atmosphere within the recess in which that electric fuse unit is disposed from the atmospheres in the other recesses.

It will be noted that the strain wires 132 are placed under tension, the springs 122 are placed under compression, and the indicators 124 are moved to their retracted positions prior to the time the electric fuse units are inserted within the recesses in the housing. This is desirable because its makes possible full inspection and checking of the indicators and strain wires in their normal positions before the electric fuse units are disposed within the housing 20.

The goifsets 74 and 84 in the terminals 70 and 80 are important because they enable the prongs 76 and 86 of those terminals to be close together while also enafbling the distances between the confronting faces of the upper portions of those terminals 70 .and 80 to be almost as great as the lengths of the recesses 3S, 42 and 46. The close spacings of the prongs 76 and 86 of the terminals70 and 80' are important inreducing the overall size of the receptacle for the electric fuse, and in-reducing the spacings between the clips Afor rthose prongs and :adjacent conductive parts of that receptacle. The larger spacings between the confronting faces of the upper portions of the terminals 70 and 80 are important in providing suiciently large arc-interrupting gaps to make sure that any arcs, which form when the fusible elements fuse, will `be extinguished. The offsets 74 and 84 are additionally desirable because they provide the room which the seals i need to fully encircle the prongs 76 and 86 of the terminals 7 0 and 80.

The open top of the housing 20 is important in eliminating any blind spots which could permit voids in the filling material 162 to escape detection. While the filling mat 13 terial 162 is solid in form, it is composed of particles of such small size and with such a small angle of set that as the various recesses, 38, 42 and 46 are filled, that filling ma-terial will flow into position around the electric fuse units and completely obviate any appreciable voids. As a result, when the filling material 162 is raised to the level of the upper surface of the housing 20, the person filling the housing 20 will know that all voids larger than the size of the particles used in the filling material 162 will have been obviated. This is important because it assures each fusible element 110 of full heat transfer therefrom to adjacent filling material 162, and also makes certain that the compressive forces applied by the closure 136 and the pad 152 will compress the filling material 162,

The electric fuse units provided by the present invention have vertically-alined, horizontally-spaced rows of fusibleelements 110. Furthermore, the fusible elements 110 in the outer rows aresbaggered relative to the fusible elements in the inner rows; and hence each fusible element 110 has an optimum quantity of filling material 162 surrounding it.

The strain wire 132 is made of Advance wire; and this is desirable because that wire is quite strong and has a high resistance. Because that wire has a high resistance, it will be certain to blow before the wire 130 blows. As a result, the strain wire 132 will be sure of releasing the indicator 124 whenever the fusible elements 110 of one or more of the electric fuse units blow The socket 56 in the bottom of the housing 20v can coact with a pin in the receptacle for that housing to permit the acceptance of that housing while preventing the acceptance of housings for electric fuses of different rating. By using different combinations of size, shape and location of sockets 56 for the housings 20 and of complementary pins in the receptacles, it is possible to establish a large range of fuse ratings 4and to make sure that only electric fuses of the proper rating can be used in any given receptacle.

Whereas the drawing and accompanying description have shown'and described a preferred embodiment of the present invention, it should be apparent to those skilled in the art that various changes may be made in the form of the invention without affecting the scope thereof.

What I claim is:

1. A11 electric fuse that comprises:

(a) a housing,

(b) said housing being hollow and having a plurality of partitions therein to form a plurality of recesses therein,

(c) said recesses having openings in the bottoms therelof which communicate with the bottom surface of said housing,

(d) a plurality of electric fuse units disposed in said plurality of recesses in said housing,

(e) each of said electric fuse units having a pair of terminals and a plurality of fusible elements,

(f) the terminals of said electric fuse units having prongs on the lower ends thereof which extend through said openings in the 'bottoms of said recesses and which serve as plug in terminals for said electric fuse,

(g) said fusible elements being secured to said pairs of terminals before said electric fuse units are telescoped into said recesses in said housing,

(h) said recesses in said housing being formed so said termin-als of said electric fuse units are moved in directions which are generally parallel Ito the axes of said terminals as said electric fuse units are telescoped into said recesses,

(i) said recesses having surfa-ces therein which engage the sides of the terminals of said electric fuse units to hold said electric fuse units solidly against sideways movement relative to said housing and which 14 permit endwise movement of said electric fuse units #after said electric fuse units are telescoped within said recesses,

(j) each of said electric fuse units being adapted to protect a different electric circuit, 4

(k) the top of said housing being open but normally being closed by a closure,

(l) seals that surround and engage said prongs of said terminals of said electric fuse units and that engage the inner surfaces of said recesses and that coact with said prongs to `close and seal said openings in the bottoms of said recesses,

(m) arc-quenching ller material disposed within said recesses,

(n) said electric fuse units being open in nature so said arc-quenching filler material can ow freely into engagement with said fusible elements of said electric fuse units after said electric fuse units have been telescoped into said recesses, and

(o) .a plate of resilient material that underlies said closure and overlies the upper ends of said terminals of said electric fuse units and overlies said arcquenching filler material when said electric fuse units are telescoped within said recesses,

(p) said closure being held in sufficiently intimate engagementl with said housing to compress said plate of resilient material,

(q) said plate of `resilient material applying pressure to said arc-quenching filler material and forcing said tare-quenching filler material into intimate engagement with said fusible elements of said electric fuse units,

(r) said seals applying pressure to said terminals to urge said terminals toward said top of said housing,

(s) said plate of resilient material applying pressure to said terminals to urge said terminals toward said bottoms of said recesses and coacting with said seals to resiliently mount said electric fuse units within said recesses.

2. An electric fuse that comprises:

(a) a housing,

('b) said housing having a recess therein,

(c) :an electric fuse unit disposed within said recess in said housing, (d) said electric fuse unit having a pair of terminals and a plurality of fusible elements,

(e) said fusible elements extending between, and being directed transversely of, said terminals,

(f) said fusible elements being spaced laterally and longiutdinally of said terminals,

(g) the top of said housing being open but normally being closed by a closure,

(h) free owing arc-quenching filler material disposed within said recess in said housing,

(i) said electric fuse unit being open in nature so said.

arc-quenchingiiller material can iiow freely between,

around and into engagement with said fusible ele.

ments of said electric fuse unit yafter said electric fuse unit has been telescoped into said recess in said housing, and

(j) a plate of resilient, compressible material that underlies said closure .and overlies said arc-quenching filler material when said electric fuse unit is telescoped within said recess in said housing,

(k) said arc-quenching filler material, whenever; said plate of resilient material is overlying and engaging said arc-quenching filler material but is an un-compressed state, substantially completely filling said recess in said housing,

(l) said closure thereafter being held in sufficiently intimate engagement with said Ahousing to compress said plate of resilient material,

(m) said plate of resilient material responding to the compression thereof lby said closure to apply pressure to said arc-quenching filler material and thereby l force said arc-quenching filler `material into intimate engagement with said fusible elements of said electric fuse unit,

(n) the free-flowing nature of said filler material enabling said ller material to respond to the pressure applied thereto by said plate of resilient material to apply substantially equal pressures to said fusible elements,

3. An electric fuse that comprises:

(a) a housing,

(b) said housing having a recess therein,

(c) an electric fuse unit disposed within said recess in said housing,

(d) said electric fuse unit having a pair of terminals and a fusible element connected to and extending between said terminals,

(e) said electric fuse unit being bodily movable as a unit wit-hin said recess in said housing,

(f) said housing having a top that is open,

(g) a closure for said open top of Isaid housing, and

(h) a plate of resilient material that underlies and engages said closure and overliesand engages the upper ends of said termin-als of said electric fuse unit when said electric fuse unit is telescoped within said recess in said housing,

(i) said plate of resilientrmaterial spacing said upper ends of said terminals from said closure and thereby `resiliently mounting said electric fuse unit in said recess in said housing,

4. An electric fuse that comprises:

(a) a housing with a bottom surface,

(b) said housing having a recess therein which extends generally perpendicularly relative to said bottom surface,

(c) said recess having openings in the bottom thereof which communicate with said bottom surface of said housing and which are generally perpendicularly relative to said bottom surface of said housing,

(d) an electric fuse unit disposed Within said recess in said housing, s

(e) said electric fuse unit having a pair of terminals with faces that are disposed within said recess and that confront each other and a fusible element connected to and extending between said confronting faces of terminals,

(f) the terminals of said electric fuse unit having integrally formed prongs on the lower ends thereof which extend through said openings in the bottom of said recess and which project beyond said bottom surface of said housing to serve as plug in terminals for said electric fuse, Y

(g) said terminals of said electric fuse units being offset intermediate the ends thereof and within said recess to space said confronting faces thereof further apart than the prongs thereof,

(h) the spacing between .the prongs of the terminals of .said electric fuse unit being great enough to prevent flashover and to prevent current leakage,

(i) the spacing between said confronting faces of the terminals of said electric fuse unit being great enough to insure extinction of any arcs that might form as said fusible element of said electric fuse unit blows,

and

(j) the top of said housing being open but normally being closed by a closure,

(k) said terminals being generally flat, elongated metal .plates that engage and are confined and guided by the Walls of said recess.

5. An electric fuse for a plural-phase electric circuit that comprises:

(a) 'a hollow housing (b) a plurality of partitions in -said hollow housing that (c)` a plurality of open-type electric fuse units disposed in said plurality of recesses,

(d) said electric fuse units having prongs that extend through a wall of said housing to serve as plug in terminals for said electric fuse,

(e) each of said electric fuse units being connected in a different phase of said plural-phase electric circuit and being adapted to protect a different phase of said plural-phase electric circuit,

(f) said partitions preventing flashover between said different phases of said plural-phase electric circuit,

(g) said housing having further walls and a closure that coact with the rst said wall to prevent the escape of vapors and gases from said housing,

(h) said partitions coacting with said one wall and said closure and some of said further walls to keep vapors and gases developed in one of said recesses from passing to and entering another of said recesses, and

(i) arc-quenching filler material disposed within each of said recesses in engagement with said open-type electric fuse units,

(j) said arc-quenching ller material conducting heat from said electric fuse units directly to said one wall and said closure and said further walls to enable said one wall and said closure and said further walls to radiate said heat into the free air surrounding said fuse. Y

6. An electric fuse that comprises:

(a) ahousing,

(b) a recess in said housing, and

(c) an electric fuse unit that telescopes into said recess in said housing, v

(d) said electric fuse unit having a pair of terminals with generally plane confronting faces and a plurality of fusible elements extending vbetween and being secured to .said confronting faces of said terminals,

(e) said fusible elements being generally perpendicular to said confronting faces of said terminals,

(f),said fusible elements beingsecured to said confronting faces of said terminals before said electric fuse unit is telescoped into said confronting faces of said recess in said housing,

(g) said fusible elements being spaced laterally and being spaced longitudinally of said terminals,

(h) said fusible elements coacting with said terminals to constitute readily-handled, open-type electric fuse units,

(i) said terminals being complete and requiring no modifications thereof or additions thereto after said electric fuse unit has been telescoped into said recess in said housing, and

v(j) free-flowing, arc-extinguishing, filler material disposed within recess in said housing in engagement with said fusible elements,

(k) said recess in said housing being formed so said terminals of said electric fuse unit are moved in a direction which is generally parallel to said confronting faces of said terminals and which is generally perpendicular to said fusible elements as said electric fuse unit is telescoped into said recess.

7. An electric fuse that comprises:

(a) ahousing,

(b) said housing having a recess therein,

(c) an electric fuse unit disposed within said recess in said housing, A

(d) said electric fuse unit having a pair of terminals with generally plane confronting faces and a fusible element connected to and extending between said confronting faces of said terminals,

(e) said fusible element being secured to said confronting faces of said terminals before said electric fuse unit is telescoped into said recess in said housing,

(f) said recess in said housing being formed so said terminals are moved in a direction which is generally parallel to said confronting faces of said terminals and which is generally perpendicular to said fusible elements as said electric fuse unit is telescoped into said recess in said housing,

(g) said recess having surfaces therein which engage the sides of said terminals of said electric fuse unit to hold said electric fuse unit solidly against sideways movement relative to said housing after said electric fuse unit is telescoped within said recess, and

(h) resilient material that engages said terminals and thereby resiliently resists movement of said electric fuse unit in said direction after said electric fuse unit is telescoped within said recess,

(i) said terminals being complete and requiring no modifications thereof r additions thereto after said electric fuse unit has been telescoped-into said recess in said housing, and (j) free-flowing, arc-extinguishing, filler material disposed within recess in said housing in engagement with said fusible elements,

(k) said resilient material resiliently mounting said electric fuse unit within said recess.

8. An electric fuse that comprises:

(a) ahousing,

(b) said housing having a recess therein,

(c) an electric fuse unit disposed within said recess in said housing,

(d) said electric fuse unit having a pair of terminals and a plurality of fusible elements,

(e) said fusible elements extending between, and being directed transversely of, said terminals,

(f) said fusible elements being spaced laterally and longitudinally of said terminals,

(g) said fusible elements being secured to said terminals before said electric fuse unit is telescoped into said recess in said housing,

(h) free-flowing arc-quenching filler material disposed within said recess in said housing,

(i) a closure for said open top of said housing, and

(j) said housing having a top that is open,

(k) saidelectric fuse unit being open in nature so said arc-quenching filler material can ow freely between, around and into engagement with said fusible elements of said electric fuse unit after said electric fuse unit has been telescoped into said recess in said hous- 111g,

(l) said arc-quenching filler material being maintained under presure t0 force it into intimate engagement with said fusible elements of said electric fuse unit,

(m) the free-flowing nature of said ller material enabling said filler material to lrespond to the pressure applied thereto to apply substantially equal pressures to said fusible elements.

References Cited by the Examiner UNITED STATES PATENTS 531,355 12/1894 Ashley 200-126 601,286 3/1898 Schwedtmann 2004129 633,576 9/1899 Downes 200-114 1,646,629 10/1927 Ogle 20G-135 2,209,823 7/ 1940 Lohausen 200-'120 2,794,096` 5/ 1957 Kozacka 200-117 2,800,557 7/1957 Swain 200-120 2,834,852 5/1958 Swain et al. 200-120 2,920,164 1/1960 Edsall 200-116.5 2,950,370 8/1960 Swain 20G-114.6 3,015,709 1/ 1962 Bodenschatz ZOO-116.5 3,139,499 6/1964 Cosgrove 200-133 FOREIGN PATENTS 811,555 1/1937 France. 1,129,716 9/1956 France. 1,164,019 4/1958 France.

20,483 9/ 1902 Great Britain. 167,713 8/ 1921 Great Britain. 295,899 5/1932 Italy.

OTHER REFERENCES German application, 1,084,359, June 1960.

BERNARD A. GILHEANY, Primm Examiner. 

1. AN ELECTRIC FUSE THAT COMPRISES: (A) A HOUSING, (B) SAID HOUSING BEING HOLLOW AND HAVING A PLURALITY OF PARTITIONS THEREIN TO FORM A PLURALITY OF RECESSES THEREIN, (C) SAID RECESSES HAVING OPENINGS IN THE BOTTOMS THEREOF WHICH COMMUNICATE WITH THE BOTTOM SURFACE OF SAID HOUSING, (D) A PLURALITY OF ELECTRIC FUSE UNITS DISPOSED IN SAID PLURALITY OF RECESSES IN SAID HOUSING, (E) EACH OF SAID ELECTRIC FUSE UNITS HAVING A PAIR OF TERMINALS AND A PLURALITY OF FUSIBLE ELEMENTS, (F) THE TERMINALS OF SAID ELECTRIC FUSE UNITS HAVING PRONGS ON THE LOWER ENDS THEREOF WHICH EXTEND THROUGH SAID OPENINGS IN THE BOTTOMS OF SAID RECESSES AND WHICH SERVE AS "PLUG IN" TERMINALS FOR SAID ELECTRIC FUSE, (G) SAID FUSIBLE ELEMENTS BEING SECURED TO SAID PAIRS OF TERMINALS BEFORE SAID ELECTRIC FUSE UNITS ARE TELESCOPED INTO SAID RECESSES IN SAID HOUSING, (H) SAID RECESSES IN SAID HOUSING BEING FORMED SO SAID TERMINALS OF SAID ELECTRIC FUSE UNITS ARE MOVED IN DIRECTIONS WHICH ARE GENERALLY PARALLEL TO THE AXES OF SAID TERMINALS AS SAID ELECTRIC FUSE UNITS ARE TELESCOPED INTO SAID RECESSES, (I) SAID RECESSES HAVING SURFACES THEREIN WHICH ENGAGE THE SIDES OF THE TERMINALS OF SAID ELECTRIC FUSE UNITS TO HOLD SAID ELECTRIC FUSE UNITS SOLIDLY AGAINST SIDEWAYS MOVEMENT RELATIVE TO SAID HOUSING AND WHICH PERMIT ENDWISE MOVEMENT OF SAID ELECTRIC FUSE UNITS AFTER SAID ELECTRIC FUSE UNITS ARE TELESCOPED WITHIN SAID RECESSES, (J) EACH OF SAID ELECTRIC FUSE UNITS BEING ADAPTED TO PROTECT A DIFFERENT ELECTRIC CIRCUIT, (K) THE TOP OF SAID HOUSING BEING OPEN BUT NORMALLY BEING CLOSED BY A CLOSURE, (L) SEALS THAT SURROUND AND ENGAGE SAID PRONGS OF SAID TERMINALS OF SAID ELECTRIC FUSE UNITS AND THAT ENGAGE THE INNER SURFACES OF SAID RECESSES AND THAT COACT WITH SAID PRONGS TO CLOSE AND SEAL SAID OPENINGS IN THE BOTTOMS OF SAID RECESSES, (M) ARC-QUENCHING FILLER MATERIAL DISPOSED WITHIN SAID RECESSES, (N) SAID ELECTRIC FUSE UNITS BEING OPEN IN NATURE SO SAID ARC-QUENCHING FILLER MATERIAL CAN FLOW FREELY INTO ENGAGEMENT WITH SAID FUSIBLE ELEMENTS OF SAID ELECTRIC FUSE UNITS AFTER SAID ELECTRIC FUSE UNITS HAVE BEEN TELESCOPED INTO SAID RECESSES, AND (O) A PLATE OF RESILIENT MATERIAL THAT UNDERLIES SAID CLOSURE AND OVERLIES THE UPPER ENDS OF SAID TERMINALS OF SAID ELECTRIC FUSE UNITS AND OVERLIES SAID ARCQUENCHING FILLER MATERIAL WHEN SAID ELECTRIC FUSE UNITS ARE TELESCOPED WITHIN SAID RECESSES, (P) SAID CLOSURE BEING HELD IN SUFFICIENTLY INTIMATE ENGAGEMENT WITH SAID HOUSING TO COMPRESS SAID PLATE OF RESILIENT MATERIAL, (Q) SAID PLATE OF RESILIENT MATERIAL APPLYING PRESSURE TO SAID ARC-QUENCHING FILLER MATERIAL AND FORCING SAID ARC-QUENCHING FILLER MATERIAL INTO INTIMATE ENGAGEMENT WITH SAID FUSIBLE ELEMENTS OF SAID ELECTRIC FUSE UNITS, (R) SAID SEALS APPLYING PRESSURE TO SAID TERMINALS TO URGE SAID TERMINALS TOWARD SAID TOP OF SAID HOUSING, (S) SAID PLATE OF RESILIENT MATERIAL APPLYING PRESSURE TO SAID TERMINALS TO URGE SAID TERMINALS TOWARD SAID BOTTOMS OF SAID RECESSES AND COACTING WITH SAID SEALS TO RESILIENTLY MOUNT SAID ELECTRIC FUSE UNITS WITHIN SAID RECESSES. 